The overall goal of this proposal is to continue the population- based Registry of incident insulin-dependent diabetes mellitus (IDDM) that was started with NIH funding in 1983 in the State of Colorado. Two new protocols are also proposed as natural extensions of the core Registry. One will describe the level of glucose control in persons with IDDM, statewide; and the second will characterize Hispanics with IDDM, who were found during the first grant period to have only one-half the risk of Anglo persons with IDDM. The specific aims are: 1) To determine the incidence of IDDM under the age of 18 years by sociodemographic, temporal, and ethnic variables for persons in the state of Colorado 2) To prospectively estimate the level of blood glucose control using a mailed filter paper method for glycosylated hemoglobin 3) To characterize Hispanic persons with IDDM on an epidemiologic, clinical, racial, and immunological basis compared to Anglos. These specific aims will be achieved through 4 principal activities. First, physician-based case-ascertainment will be maintained and validated. Second, follow-up will be continued for acute and chronic complications as determined by questionnaire to assess the natural histroy of IDDM. Third, glycosylated hemoglobins will be obtained to characterize glucose control and prepare for a detailed complications review. Fourth, Hispanics and appropriate Anglos will be studied to determine if clinical, biochemical, immunologic, and genetic characteristics differ for Hispanics with IDDM